One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,4)(3,7,8,6)(9,10)(11,16)(12,18)(13,22)(14,19)(15,17)(20,23)(21,24)(25,26,32,31)(27,28,34,30)(29,33,39,38)(35,36,40,37)(1,3,5,8)(2,6,4,7)(9,11)(10,16)(12,19)(13,21)(14,18)(15,20)(17,23)(22,24)(25,27)(26,30)(28,31)(29,35)(32,34)(33,37)(36,38)(39,40)(10,17)(11,20)(12,22)(14,21)(25,28,32,30)(26,27,31,34)(29,37,39,36)(33,40,38,35)(9,12,15,22)(10,18,17,13)(11,19,20,24)(14,23,21,16)(25,29,32,39)(26,33,31,38)(27,35,34,40)(28,36,30,37)(9,13,15,18)(10,12,17,22)(11,21,20,14)(16,19,23,24)(25,30,32,28)(26,34,31,27)(29,37,39,36)(33,40,38,35)(1,4,5,2)(3,7,8,6)(9,14,15,21)(10,19,17,24)(11,18,20,13)(12,23,22,16)(25,31,32,26)(27,28,34,30)(29,38,39,33)(35,36,40,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.